Hey guys I have a 95 150 Supercab 4x4 5.0. It had been sitting for about 8 months with brake problems and I recently had it taken in and had about 850 worth of brake and other work done to it. I had 4 new tires put on, all fluids changed and something called a transtech done to the transmission (it apparently drains all the fluid and then they replace it). I also had a rear ABS sensor put on as my ABS light was showing up on the dashboard. Anyways, after I got my truck back, it runs fine, however I have noticed that my speedometer stopped working and the cruise control wont work either. The overdrive off light that is on my gear shift lever also blinks on and off, there is no apparent code it just blinks on and off and the transmission shifts and works fine. If I am in park or below about ten mph, the OD light does not blink and the speedo needle jumps up and down erratically, but as I pick up speed the needle goes down to 0 and the OD light starts blinking. On another note Ive noticed the last couple of times Ive started my truck up, the engine turns over and idles rough for about 5 minutes and then after it warms up it idles fine and runs strong, there does seem to be a slight miss but im thinking its in one of the spark plugs. Do you guys have any idea about what might be causing the light as well as the rough startup idle?

 

You have a bad or miss installed VSS sensor on the top of the rear end.
They may have also messed up the tone ring when they changed it.
Some other years called this sensor the DSS or ABS sensor.

Why did you have it replaced if it was working fine?

 

it was showing an ABS light before i took it in, thats why i had the sensor replaced.

 

btw what is a tone ring?

 

The tone ring is a ring mounted on the drivers side of the carrier in your rear differential. It has evenly spaced humps on it (very closely together) and then your abs sensor, which doubles as your vss picks up the magnetic pulse off of each hump and that is how it achieves a speed signal or a lock up for the abs

 

Is the ABS light still on?

 

now it only comes on about once every other day for about 20 minutes or so, i got under the truck yesterday and wiggled the abs connector on my rear end as i was leaving work...the speedo acted like it wanted to work and the light didnt blink, but then it quit and started doing the same thing over again..blinking, erratic jumping of speedo needle etc.

 

They messed something up back there. Either the plug, the sensor or the tone ring.
Was the speedometer was working OK when you took it in?

 

yeah the last time i drove the truck before taking it in, it worked. The ABS light was coming on then, thats why i had them replace the sensor. I dont know what all they done when they installed the new one, i just know that there is a new one on my rear end housing now. The only thing that I think they did inside the rear differential was to pop the bottom of the cover and drain the fluid and replace it with new.

 

You could try unplugging the ABS module under the dash and see if the speedometer starts working again.
If not try checking the voltage from the rear end with a meter.
Put the rear end up on stands and run it slowly up to about 30 MPH.
Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts (at connector C143) as vehicle speed increases from 0 to 30 mph?

C143 is located at the drivers side hood hinge.

 

Here is a wiring diagram of the 1995 system:


C143:


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